To connect Samsung Galaxy to computer in USB drive you'll need to set the cable used to connect the smartphone to the USB port of the computer. Then connect the other end of the cable to the unit and wait for menu operation on the screen of the device.
In the menu that appears, click on the "Connect USB storage". After selecting this option on the computer screen a notification will appear about the beginning of the installation of required drivers, after which you will be asked to perform actions to view content of the connected drive. To see the folders on the device, select the option "Open to view files". If your phone also has a removable flash drive, it will also be open on the computer screen in view mode folders.
In addition to connecting in disk drive mode you can also use the Samsung Kies program that comes in one package with the device on a dedicated disk with the software. Install the drive in computer and select to install Samsung Kies. You can also download the installer for the application from the official Samsung website in the relevant section.
After installation run through the shortcut on the desktop and connect your smartphone with the USB cable that comes with the device. The phone will be determined by the program and you will be able to manage both the content and the phone book.
Using Samsung Kies, you can also save the necessary data of phone as a backup to use in case of problems in the functioning of the apparatus.
If you want to change the connection mode of the phone to the computer without disconnecting the phone, or to determine the setting to use the phone as a USB drive by default, go in menu "Settings" - "Network" - "USB Connection" and tick the box next to the desired menu item.